Abstract The repair of large cartilage lesions, which often lead to osteoarthritis (OA), remains a significant clinical problem with few good treatment options. Previous work at Cytex has focused on the developing of a 3D woven textile scaffold for cartilage repair, designed to function immediately upon implantation, while encouraging cell ingrowth, proliferation, and subsequent tissue development. By combining this proprietary 3D woven implant with adipose- derived stem cells (ASCs), we have demonstrated the ability to generate large, anatomically shaped cartilage constructs with biomimetic mechanical properties. Nevertheless, for a cell-based cartilage therapy to be successful in an OA patient, it must withstand the catabolic effects of joint inflammation, which are mediated by the action of elevated levels of pro-inflammatory cytokines such as interleukin-1 (IL-1) and tumor necrosis factor alpha (TNFa). However, because of the pleiotropic role of IL-1 and TNFa in vivo, long-term sustained anti- cytokine therapy is not recommended. Therefore, the objective of this project is to evaluate the safety and efficacy of an engineered functional cartilage replacement capable of protecting itself from OA inflammation by producing an anti-cytokine therapy. To this end, we propose to use an inflammation-responsive promoter to drive expression of therapeutic factors, specifically, IL-1 receptor antagonist and soluble TNF receptor 1. This will create an auto-regulated system in which cells express and secrete anti-cytokine proteins only when inflammatory signaling is present. In Aim 1, we will modulate the lentiviral transduction process in an effort to minimize the risk of genetic side effects in our biomimetic cartilage implant. Our goal is to minimize the number of viral integration events in each cell, while maintaining a high transduction efficiency, so that the ASCs in our implant can effectively deliver the anti-cytokine therapy. In Aim 2, our engineered cartilage will be implanted subcutaneously in an inflammatory mouse model to test the construct?s ability to sense and prevent catabolic degradation. Serum will be collected from the mice longitudinally to measure the levels of inflammatory cytokines present in the model, as well as the levels of anti-cytokine therapeutics produced by our implant in direct response to the inflammatory cytokines. At sacrifice, the cartilage constructs will be excised and assessed histologically, biochemically, and biomechanically to quantify any degradative changes that have occurred in the tissue. Additionally, all major organ systems of the mice will be examined histologically to assess the safety of implanting transduced cells and utilizing anti-cytokine therapy. This proposal addresses the clinical need for large functional cartilage replacements that can thrive in an inflamed osteoarthritic joint, and could, as a consequence, have a major impact on the treatment paradigm of this disease.